/*
 * @(#)EqualFunction.java
 *
 * Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
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 *
 * You acknowledge that this software is not designed or intended for use in
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 */

package org.wso2.balana.cond;

import org.wso2.balana.ctx.EvaluationCtx;

import org.wso2.balana.XACMLConstants;
import org.wso2.balana.attr.AnyURIAttribute;
import org.wso2.balana.attr.AttributeValue;
import org.wso2.balana.attr.Base64BinaryAttribute;
import org.wso2.balana.attr.BooleanAttribute;
import org.wso2.balana.attr.DateAttribute;
import org.wso2.balana.attr.DateTimeAttribute;
import org.wso2.balana.attr.DayTimeDurationAttribute;
import org.wso2.balana.attr.DNSNameAttribute;
import org.wso2.balana.attr.DoubleAttribute;
import org.wso2.balana.attr.HexBinaryAttribute;
import org.wso2.balana.attr.IntegerAttribute;
import org.wso2.balana.attr.IPAddressAttribute;
import org.wso2.balana.attr.RFC822NameAttribute;
import org.wso2.balana.attr.StringAttribute;
import org.wso2.balana.attr.TimeAttribute;
import org.wso2.balana.attr.YearMonthDurationAttribute;
import org.wso2.balana.attr.X500NameAttribute;

import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Set;

/**
 * A class that implements all the *-equal functions. It takes two operands of
 * the appropriate type and returns a <code>BooleanAttribute</code> indicating
 * whether both of the operands are equal. If either of the operands is
 * indeterminate, an indeterminate result is returned.
 * 
 * @since 1.0
 * @author Steve Hanna
 * @author Seth Proctor
 */
public class EqualFunction extends FunctionBase {

	/**
	 * Standard identifier for the string-equal function.
	 */
	public static final String NAME_STRING_EQUAL = FUNCTION_NS + "string-equal";

	/**
	 * Standard identifier for the boolean-equal function.
	 */
	public static final String NAME_BOOLEAN_EQUAL = FUNCTION_NS
			+ "boolean-equal";

	/**
	 * Standard identifier for the integer-equal function.
	 */
	public static final String NAME_INTEGER_EQUAL = FUNCTION_NS
			+ "integer-equal";

	/**
	 * Standard identifier for the double-equal function.
	 */
	public static final String NAME_DOUBLE_EQUAL = FUNCTION_NS + "double-equal";

	/**
	 * Standard identifier for the date-equal function.
	 */
	public static final String NAME_DATE_EQUAL = FUNCTION_NS + "date-equal";

	/**
	 * Standard identifier for the time-equal function.
	 */
	public static final String NAME_TIME_EQUAL = FUNCTION_NS + "time-equal";

	/**
	 * Standard identifier for the dateTime-equal function.
	 */
	public static final String NAME_DATETIME_EQUAL = FUNCTION_NS
			+ "dateTime-equal";

	/**
	 * Standard identifier for the dayTimeDuration-equal function.
	 */
	public static final String NAME_DAYTIME_DURATION_EQUAL = FUNCTION_NS
			+ "dayTimeDuration-equal";

	/**
	 * Standard identifier for the yearMonthDuration-equal function.
	 */
	public static final String NAME_YEARMONTH_DURATION_EQUAL = FUNCTION_NS
			+ "yearMonthDuration-equal";

	/**
	 * Standard identifier for the anyURI-equal function.
	 */
	public static final String NAME_ANYURI_EQUAL = FUNCTION_NS + "anyURI-equal";

	/**
	 * Standard identifier for the x500Name-equal function.
	 */
	public static final String NAME_X500NAME_EQUAL = FUNCTION_NS
			+ "x500Name-equal";

	/**
	 * Standard identifier for the rfc822Name-equal function.
	 */
	public static final String NAME_RFC822NAME_EQUAL = FUNCTION_NS
			+ "rfc822Name-equal";

	/**
	 * Standard identifier for the hexBinary-equal function.
	 */
	public static final String NAME_HEXBINARY_EQUAL = FUNCTION_NS
			+ "hexBinary-equal";

	/**
	 * Standard identifier for the base64Binary-equal function.
	 */
	public static final String NAME_BASE64BINARY_EQUAL = FUNCTION_NS
			+ "base64Binary-equal";

	/**
	 * Standard identifier for the ipAddress-equal function.
	 */
	public static final String NAME_IPADDRESS_EQUAL = FUNCTION_NS_2
			+ "ipAddress-equal";

	/**
	 * Standard identifier for the dnsName-equal function.
	 */
	public static final String NAME_DNSNAME_EQUAL = FUNCTION_NS_2
			+ "dnsName-equal";

	// private mapping of standard functions to their argument types
	private static HashMap typeMap;

	/**
	 * Static initializer sets up a map of standard function names to their
	 * associated datatypes
	 */
	static {
		typeMap = new HashMap();

		typeMap.put(NAME_STRING_EQUAL, StringAttribute.identifier);
		typeMap.put(NAME_BOOLEAN_EQUAL, BooleanAttribute.identifier);
		typeMap.put(NAME_INTEGER_EQUAL, IntegerAttribute.identifier);
		typeMap.put(NAME_DOUBLE_EQUAL, DoubleAttribute.identifier);
		typeMap.put(NAME_DATE_EQUAL, DateAttribute.identifier);
		typeMap.put(NAME_TIME_EQUAL, TimeAttribute.identifier);
		typeMap.put(NAME_DATETIME_EQUAL, DateTimeAttribute.identifier);
		typeMap.put(NAME_DAYTIME_DURATION_EQUAL,
				DayTimeDurationAttribute.identifier);
		typeMap.put(NAME_YEARMONTH_DURATION_EQUAL,
				YearMonthDurationAttribute.identifier);
		typeMap.put(NAME_ANYURI_EQUAL, AnyURIAttribute.identifier);
		typeMap.put(NAME_X500NAME_EQUAL, X500NameAttribute.identifier);
		typeMap.put(NAME_RFC822NAME_EQUAL, RFC822NameAttribute.identifier);
		typeMap.put(NAME_HEXBINARY_EQUAL, HexBinaryAttribute.identifier);
		typeMap.put(NAME_BASE64BINARY_EQUAL, Base64BinaryAttribute.identifier);
		typeMap.put(NAME_IPADDRESS_EQUAL, IPAddressAttribute.identifier);
		typeMap.put(NAME_DNSNAME_EQUAL, DNSNameAttribute.identifier);
	}

	/**
	 * Returns an <code>EqualFunction</code> that provides the type-equal
	 * functionality over the given attribute type. This should be used to
	 * create new function instances for any new attribute types, and the
	 * resulting object should be put into the <code>FunctionFactory</code>
	 * (instances for the standard types are pre-installed in the standard
	 * factory).
	 * <p>
	 * Note that this method has the same affect as invoking the constructor
	 * with the same parameters. This method is provided as a convenience, and
	 * for symmetry with the bag and set functions.
	 * 
	 * @param functionName
	 *            the name to use for the function
	 * @param argumentType
	 *            the type to operate on
	 * 
	 * @return a new <code>EqualFunction</code>
	 */
	public static EqualFunction getEqualInstance(String functionName,
			String argumentType) {
		return new EqualFunction(functionName, argumentType);
	}

	/**
	 * Creates a new <code>EqualFunction</code> object that supports one of the
	 * standard type-equal functions. If you need to create an instance for a
	 * custom type, use the <code>getEqualInstance</code> method or the
	 * alternate constructor.
	 * 
	 * @param functionName
	 *            the standard XACML name of the function to be handled by this
	 *            object, including the full namespace
	 * 
	 * @throws IllegalArgumentException
	 *             if the function isn't standard
	 */
	public EqualFunction(String functionName) {
		this(functionName, getArgumentType(functionName));
	}

	/**
	 * Creates a new <code>EqualFunction</code> object.
	 * 
	 * @param functionName
	 *            the standard XACML name of the function to be handled by this
	 *            object, including the full namespace
	 * @param argumentType
	 *            the standard XACML name for the type of the arguments,
	 *            inlcuding the full namespace
	 */
	public EqualFunction(String functionName, String argumentType) {
		super(functionName, 0, argumentType, false, 2,
				BooleanAttribute.identifier, false);
	}

	/**
	 * Private helper that returns the type used for the given standard
	 * type-equal function.
	 */
	private static String getArgumentType(String functionName) {
		String datatype = (String) (typeMap.get(functionName));

		if (datatype == null)
			throw new IllegalArgumentException("not a standard function: "
					+ functionName);

		return datatype;
	}

	/**
	 * Returns a <code>Set</code> containing all the function identifiers
	 * supported by this class.
	 * 
	 * @return a <code>Set</code> of <code>String</code>s
	 */
	public static Set getSupportedIdentifiers() {
		return Collections.unmodifiableSet(typeMap.keySet());
	}

	/**
	 * Evaluate the function, using the specified parameters.
	 * 
	 * @param inputs
	 *            a <code>List</code> of <code>Evaluatable</code> objects
	 *            representing the arguments passed to the function
	 * @param context
	 *            an <code>EvaluationCtx</code> so that the
	 *            <code>Evaluatable</code> objects can be evaluated
	 * @return an <code>EvaluationResult</code> representing the function's
	 *         result
	 */
	public EvaluationResult evaluate(List<Evaluatable> inputs,
			EvaluationCtx context) {

		// Evaluate the arguments
		AttributeValue[] argValues = new AttributeValue[inputs.size()];
		EvaluationResult result = evalArgs(inputs, context, argValues);
		if (result != null)
			return result;

		if (argValues[1] instanceof StringAttribute
				&& XACMLConstants.ANY.equals(((StringAttribute) argValues[1])
						.getValue())) {
			return EvaluationResult.getInstance(true);
		}

		// Now that we have real values, perform the equals operation
		return EvaluationResult.getInstance(argValues[0].equals(argValues[1]));
	}

}
